1. Field of the Invention
The present invention relates to electronic devices which can produce a randomly variable output voltage or frequency, and devices which can deliver power to a load at a rate proportional to a randomly generated voltage level.
2. Description of the Prior Art
It is often desirable to randomly vary the power output to a load. The load can be, for example, Christmas tree lights, advertising display lighting, or a device providing a mechanical output proportional to a voltage input. The power output to the load may be controlled by a mechanical switch such as in Christmas tree lights, which randomly opens and closes due to thermal expansion and contraction of its parts. Or the power to the load can be turned on at the receipt of a random input voltage pulse.
One method of generating random pulses is to sample the output voltage of a relatively high frequency oscillator at irregular intervals, and use the sampled value to determine the time delay until the next pulse. The irregular sampling interval is determined from the previous time delay. This type of system has a drawback in that there is a tendency for the pulses to settle into a regular rhythm. This is due to the fact that the waveform which is sampled to determine the next time delay is regular. If in the course of operation the variable time delay becomes an integral multiple of the period of the sampled waveform, the waveform is sampled at the identical point each time and the output voltage is no longer random.
This type of circuit has the further drawback that if the output voltage were to be used to control the power output to a load, the load would be abruptly switched on and off. In many applications, this effect is undesirable.